What alternative to net energy metering (NEM) with PV systems will improve the grid stability and reduce consumer dependence on it? Self-consumption energy storage PV systems are the answer.

Solar PV installations continue to grow in the residential and commercial sectors. Integrated energy storage continues to grow along with the PV installations, and both of these are growing at a strong pace in the industry.

NEM can be calculated on a daily, monthly or annual basis; most NEM agreements are calculated monthly. Whether the consumer generated energy is used by the consumer or sent back into the grid, the energy consumption is reduced at the retail rate. The problem with this setup is that most of the energy goes back into the grid during the middle of the day (solar hours) when consumer energy demand is low; this does not improve grid stability, and can make it worse. The graph below shows the typical energy consumption vs. solar energy generation for a residential customer.

PV systems with energy storage can change this with the batteries storing energy that would otherwise be sent into the grid.

The stored and redistributed solar energy will improve grid stability in residential by reducing demand during peak usage times. If time of use metering (TOU) is in place, this setup will reduce energy consumption during afternoon and evening high rate periods. This increases financial savings to the PV system owner.

The following graph shows the typical U.S. grid load demand curves for all electrical energy users.

Residential electrical energy customers with interactive PV systems are supplying power during the time of day when residential load demand is not at its peak. PV systems with energy storage can operate as self-consumption systems and improve their return on investment. Grid stability is improved to the point where grid operators can see reduced operating cost as this type of PV system penetrates more of the NEM market.

This type of PV system can also provide the customer with critical load circuits that will operate during a grid outage. Everyone wins with these systems and NEM policies are no longer a factor with the customer’s financial rate of return.